Re: Map projections: an Apache SIS - Proj.4 comparison (1/2)

[Rob Emanuele]

Thanks for the code Martin.

Let me know when you are interested in starting that up, I'll give an
update on Proj4j's progress - we might have gotten it into LocationTech's
repo by then.

Best,
Rob

On Sat, Sep 9, 2017 at 4:12 PM, Martin Desruisseaux <
martin.desruisse...@geomatys.com> wrote:

> Le 28/08/2017 à 17:34, Rob Emanuele a écrit :
>
> > Follow up question: is the benchmarking code somewhere that I can
> > build on? I'd like to compare how Proj4J would do against SIS and proj.4.
> >
> I posted a preliminary version of the benchmark code here:
>
> https://svn.apache.org/repos/asf/sis/release-test/maven/
> src/main/java/org/apache/sis/test/referencing/
> CoordinateOperationComparator.java
>
> I will try to help for Proj4J wrappers (so it can easily be added to the
> tests) later this month, after OGC meeting.
>
> Martin
>
>
>

Re: Map projections: an Apache SIS - Proj.4 comparison (1/2)

[Rob Emanuele]

Follow up question: is the benchmarking code somewhere that I can build on?
I'd like to compare how Proj4J would do against SIS and proj.4.

On Mon, Aug 28, 2017 at 11:30 AM, Rob Emanuele  wrote:

> This is great work, thanks for posting! Looking forward to the second blog
> post.
>
> On Mon, Aug 28, 2017 at 11:14 AM, Martin Desruisseaux <
> martin.desruisse...@geomatys.com> wrote:
>
>> Hello all
>>
>> In August 17th 2017, we presented an introduction to Apache Spatial
>> Information System (SIS) in the Free and Open Source Software for
>> Geospatial (FOSS4G) conference. Discussions about performance and
>> accuracy were planed, but skipped because of lack of time. We put the
>> intended content in a series of 2 blog posts. The first post, about
>> performance, is available at [1]. The key findings are:
>>
>>   * Proj.4 is generally faster than Apache SIS on Java 8. The identified
>> cause is the cost of trigonometric functions.
>>   * Some (but not all) trigonometric functions are much faster in Java
>> 9, but we have not yet benchmarked SIS on Java 9.
>>   * Despite the above, Apache SIS is sometime faster than Proj.4 (400
>> times faster in an extreme case). This can be explained by
>> mathematical work done in SIS.
>>   * Numerical results are in close agreement for map projections, but
>> can differ by 1 or 2 metres for datum shifts. This is because of
>> different ways to use the EPSG geodetic dataset ("early-binding"
>> versus "late-binding" approaches).
>>
>> More details are given at [1]. A second blog focussed on the accuracy
>> topic will be posted later.
>>
>> Martin
>>
>> [1] https://www.geomatys.com/wordpress/index.php/2017/08/28/
>> english-proj-4-versus-apache-sis-a-performance-comparison/?lang=en
>>
>>
>>
>

Re: Map projections: an Apache SIS - Proj.4 comparison (1/2)

[Rob Emanuele]

This is great work, thanks for posting! Looking forward to the second blog
post.

On Mon, Aug 28, 2017 at 11:14 AM, Martin Desruisseaux <
martin.desruisse...@geomatys.com> wrote:

> Hello all
>
> In August 17th 2017, we presented an introduction to Apache Spatial
> Information System (SIS) in the Free and Open Source Software for
> Geospatial (FOSS4G) conference. Discussions about performance and
> accuracy were planed, but skipped because of lack of time. We put the
> intended content in a series of 2 blog posts. The first post, about
> performance, is available at [1]. The key findings are:
>
>   * Proj.4 is generally faster than Apache SIS on Java 8. The identified
> cause is the cost of trigonometric functions.
>   * Some (but not all) trigonometric functions are much faster in Java
> 9, but we have not yet benchmarked SIS on Java 9.
>   * Despite the above, Apache SIS is sometime faster than Proj.4 (400
> times faster in an extreme case). This can be explained by
> mathematical work done in SIS.
>   * Numerical results are in close agreement for map projections, but
> can differ by 1 or 2 metres for datum shifts. This is because of
> different ways to use the EPSG geodetic dataset ("early-binding"
> versus "late-binding" approaches).
>
> More details are given at [1]. A second blog focussed on the accuracy
> topic will be posted later.
>
> Martin
>
> [1] https://www.geomatys.com/wordpress/index.php/2017/08/
> 28/english-proj-4-versus-apache-sis-a-performance-comparison/?lang=en
>
>
>